Heat exchanger

ABSTRACT

The present invention relates to a heat exchanger for exchanging heat between first and second fluids, said exchanger including: a casing and an exchange bundle positioned inside said casing, wherein the exchange bundle includes: a main surface which has a main width and which consists of a plurality of tubes suitable for guiding the first fluid inside said tubes; an intake of the first fluid toward an outlet of the first fluid, making it possible to guide, outside of said tubes, the second fluid; an intake of the second fluid toward an outlet of the second fluid; wherein the tubes are, at least at one first end, assembled such as to form a secondary surface having a secondary width which is smaller than the main width for coupling with the intake and/or the outlet of the first fluid; wherein the secondary surface at the first end of the tubes is formed such as to create a space between the casing and the outer surface of the secondary surface, said space being connected to the intake and/or the outlet of the second fluid.

FIELD OF THE INVENTION

The present invention relates to a heat exchanger, such as a heat exchanger intended for an automobile vehicle. The heat exchanger according to the present invention is particularly suitable for being used in engine exhaust gas conduits. This type of heat exchanger is generally called an Exhaust Gas Recirculation Cooler (EGR or EGRC exchanger).

A heat exchanger, of the type of those used in the automotive industry, and more specifically inside exhaust gas conduits of an internal combustion heat engine, in principle comprises a casing or case including, in its inside, heat exchange elements allowing exchange of heat from a first fluid to a second fluid. These elements, allowing this heat exchange may for example, comprise tubes.

These tubes located inside a heat exchanger may be present inside an exchange bundle comprising a plurality of tubes positioned essentially parallel with each other. The tubes may be positioned on one row or several rows parallel with each other. The tubes give the possibility of guiding the first fluid inside said tubes, from a first end of the exchange bundle to the second end of the exchange bundle.

The relevant tubes together define between them channels which guide the second fluid from the second end of the heat exchanger to the first end of the heat exchanger. Thus, a heat exchanger notably allows circulation as a counter-current, of a first and of a second fluid within this heat exchanger.

Other elements such as plates, fins and flow disturbers may be provided in addition to these tubes forming the exchange bundle in order to improve the heat exchange between the first and the second fluids.

Heat exchangers including a case giving the possibility of receiving, in its inside, exchange bundles are known from the prior art. The case appears as a casing comprising a plurality of walls forming the outside of the case and defining the volume in which the heat exchange is carried out. The case is in principle provided with inlets and outlets intended for the first and for the second fluid in a first and second end of the case. These inlets and outlets thus allow the heat exchanger to be respectively connected to input ducts and output ducts suitable for conducting the first and second fluids towards the heat exchanger and this, by means of the input ducts, to a final destination and this by means of the output ducts, when said first and second fluids have crossed the heat exchanger.

STATE OF THE ART

A heat exchanger, as described above, is disclosed in the German patent application DE 199 27 607. According to this document, the heat exchanger comprises a plurality of tubes obtained by means of plates stacked on each other inside a case in order to obtain tubes allowing guidance of a first fluid, from an inlet intended for this first fluid, to an outlet intended for this first fluid.

The various tubes defining between them channels allowing guidance of a second fluid, from an inlet intended for this second fluid, to an outlet intended for this second fluid. The heat exchanger according to the German patent application DE 199 27 607 is adapted for guiding the first fluid along the longitudinal direction of a case, from a first end of the case to a second end of the case. The inlet and outlet intended for the second fluid are positioned in the side walls of the case in order to allow entry and exit of said second fluid along a direction perpendicular to the direction of flow of the first fluid.

The heat exchanger according to the German patent application DE 199 27 607 has a first drawback according to which the various inlet and outlet connections of fluids are located on four different walls of the case forming the outside of the heat exchanger. The inlet and the outlet intended for the first fluid are present on the ends of the case, in the longitudinal direction of the case. The inlet and the outlet intended for the second fluid are present on the side walls of the case. The positioning of these inlets and outlets of fluids limits the possibilities of adaptation for installing the heat exchanger within an available space.

Further, the manufacturing of the heat exchanger according to patent application DE 199 27 607 limits the heat exchange between the first and the second fluid, to a portion of the length of said heat exchanger, i.e. between the inlet and the outlet intended for the second fluid. In other words, a heat exchanger between the first and the second fluid is impossible on a portion of the path of the first fluid. For this reason, a heat exchanger with the device according to the German patent application DE 199 27 607 is not optimum relatively to the outer dimensions of the heat exchanger.

Nowadays, the space intended for heat exchangers and to their components inside automobile vehicles tends to be reduced in order to integrate other devices required for the operation of the automobile vehicle. This means that the integration of a heat exchanger is more and more complex. For this reason, it is important to develop compact heat exchangers allowing relative freedom in adaptation, notably in the positioning of the input and output ducts of the first and second fluid, in order to be able to integrate as most efficiently as possible, the heat exchanger assembly into the available space.

OBJECT OF THE INVENTION

The heat exchanger according to the present invention aims at finding a remedy to the drawbacks of the known heat exchangers of the state of the art, by proposing a new design as to the formation of an exchange bundle with which it is possible to improve the compactness of said heat exchanger.

For this purpose, the invention relates to a heat exchanger giving the possibility of exchanging heat between a first and second fluid, said exchanger comprising:

-   -   a case and     -   an exchange bundle positioned inside said case,     -   wherein the exchange bundle comprises:         -   a main surface comprising a main width and formed with a             plurality of tubes suitable for guiding the first fluid             inside these tubes,         -   an inlet of the first fluid towards an outlet of the first             fluid and giving the possibility of guiding, outside these             tubes, the second fluid,         -   an inlet of the second fluid towards an outlet of the second             fluid,             wherein the tubes are, at least at one first end, assembled             so as to form a secondary surface comprising a secondary             width less than the main width for connecting to the inlet             and/or the outlet of the first fluid,             wherein the secondary surface at the first end of the tubes             is formed in order to generate a space between the case and             the outer face of the secondary surface, which space is             connected to the inlet and/or outlet of the second fluid.

According to the invention, it is possible that the tubes at a first end are assembled so as to form the secondary surface for connection to the inlet of the first fluid,

-   -   wherein the secondary surface at the first end of the tubes is         formed in order to generate a space between the case and the         outer face of the secondary surface, which space is connected to         the outlet of the second fluid.     -   and wherein the tubes are, at the second end, assembled in order         to form a secondary surface comprising a secondary width less         than the width for connection to the outlet of the first fluid,         said secondary surface at the second end of the tubes generating         a space between the case and the outer face of the secondary         surface, which space is connected to the inlet of the second         fluid.

Thus, in a first phase, by the formation and assembly of the exchange bundle according to the present invention, the inlets and outlets intended for the first and second fluid are located at opposite ends of the case. This grouping of the inlets and outlets increases the adaptation possibilities and gives the possibility of integrating, in an optimum way, the heat exchanger assembly into an available space.

Moreover, in a second phase, the secondary surface gives the possibility of connecting the second end of the tubes to the outlet generating a space for the inlet of the first fluid, has the advantage of being able to carry out heat exchange between the first and second fluid all along the path of the fluids, i.e. from their entry to their respective exit. For this reason, the efficiency of the heat exchanger is increased relatively to its outer dimensions.

According to an embodiment, the heat exchanger according to the present invention comprises a sealing element giving the possibility of covering the tubes at each of their ends.

According to an embodiment, the heat exchanger according to the present invention comprises a connecting element with which it is possible to connect at least one end of the tubes to an inlet or to an outlet by means of said connecting element.

According to an embodiment, the tubes are positioned relatively to each other so as to generate between them channels and wherein said channels include disturbers.

According to an embodiment of the present invention, the heat bundle is obtained by a plurality of plates positioned over each other, the ends of said plates being provided with a rim giving the possibility of increasing the surface between the plate and the inside of the case.

SHORT DESCRIPTION OF THE DRAWINGS

The goals, objects and features of the present invention as well as advantages thereof will become more clearly apparent upon reading the description which follows, of a preferred embodiment of a heat exchanger according to the invention, made with reference to the drawings wherein:

FIG. 1 shows an exploded perspective view, of a heat exchanger according to a first embodiment of the present invention,

FIG. 2 shows the heat exchanger according to FIG. 1, in an assembled form,

FIG. 3 illustrates the exchange bundle of the heat exchanger according to FIGS. 1 and 2,

FIG. 4 shows in detail two plates forming together a portion of the exchange bundle according to FIG. 3,

FIG. 5 schematically shows a view of the main surface of the exchange bundle,

FIG. 6 schematically shows a view of the secondary surface of the exchange bundle,

FIG. 7 illustrates an exploded perspective view of a heat exchanger according to a second embodiment of the present invention,

FIG. 8 shows the exchange bundle of the heat exchanger according to FIG. 7,

FIG. 9 illustrates in detail the end of the exchange bundle according to FIG. 8,

FIG. 10 shows an exploded perspective view of a third embodiment of the heat exchanger according to the present invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

FIG. 1 illustrates, according to an exploded perspective view, a first embodiment of a heat exchanger 10 according to the present invention. The heat exchanger 10 comprises a first element 11 and a second element 12 giving the possibility, when combined, of forming the outside of the heat exchanger 10. The combined elements 11 and 12 form a casing or “case” 11, 12 which may contain elements giving the possibility of optimizing the heat exchange between a first and a second fluid. The second element 12 comprises the various inlets and outlets of the first and of the second fluid.

The inlet 21, present in the second element 12 forms the inlet intended for the first fluid. On the opposite face, the outlet 22 forms the outlet intended for the first fluid. The inlet 31 is intended for the second fluid. The outlet 32 is intended for the second fluid.

During the use of the heat exchanger 10, the first fluid penetrates through the inlet 21 into the inside of said heat exchanger 10. Simultaneously, the second fluid penetrates into the inside of the heat exchanger 10 via the inlet 31. Thus, the heat exchanger 10 comprises an exchange bundle 13 including a stack of plates 17 forming, when combined, tubes and channels defined between said tubes. The exchange bundle 13 is illustrated in more detail in the FIGS. 3 and 4. As indicated above, the exchange bundle 13 includes a stack of plates 17 in which an assembly consisting of two plates, forms in its inside a tube allowing the first fluid to be guided from its inlet 21 to its outlet 22. Channels are defined between the different tubes and allow circulation of the second fluid from its inlet 31 to its outlet 32.

For practical reasons and with view to facilitating the references to the heat exchanger 10 as shown in FIG. 1, the dimensions “L”, “l” and “h” are indicated in FIG. 1. The letter “L” is used for referring to the largest dimension of the heat exchanger 10 and corresponds to the direction in which circulate the first and second fluid. The letter “l” is used for indicating the width of the heat exchanger 10 and the letter “h” is used for indicating the height of the heat exchanger 10.

The stack of plates 17 gives the possibility of obtaining the exchange bundle 13 and appears according to the arrangement shown in FIG. 4. The plates 17 each have an internal face, suitable for forming the inner wall of a tube and suitable for being exposed to the first fluid, and an opposite or external face. This external face is in contact with the second fluid upon using the plate 17.

FIG. 4 shows that each plate 17 is provided in its longitudinal length with a curved element. This curved element is adapted for increasing the contact surface between the end of the plates 17 (as seen in a longitudinal direction) and inside the walls of the first element 11 shown in FIG. 1. This increase in surface facilitates the braising method allowing assembly of the different elements of the heat exchanger 10 with each other and ensuring optimum contact in order to avoid possible leaks of fluids upon using the heat exchanger 10.

With view to obtaining the exchange bundle 13, the different plates 17 are positioned so that the inner face of the first plate 17 is directed towards the inner face of the second plate 17, said second plate 17 being positioned with its outer face directed towards the inner face of the third plate 17, and so forth according to the relevant number of plates.

In the heat exchanger 10 according to FIG. 1, the various plates 17 have dimensions corresponding to the dimensions inside the case 11, 12 of said heat exchanger 10. The width “l” of the plates 17, as shown in FIG. 4, corresponds to the internal width of the case 11, 12, as shown in FIG. 1.

The shape of the tubes of the exchange bundle is modified at the end of the tubes and exhibits a constriction. The exchange bundle includes in its ends, a connection surface in which the outlets of the different tubes are assembled. As shown in FIG. 3, this connection surface is suitable for being connected by means of a connecting element 14 to the outlet 32 intended for the second fluid.

FIG. 1 describes a sealing element 16 adapted in order to allow covering of the ends of the plates 17 forming together the exchange bundle 13. This sealing element 16 allows said plates 17 to be maintained together in order to avoid any possible leaks from the inside of the tubes towards the channels located outside the tubes and vice versa.

The connecting element 14 is suitable for connecting the connection surface of the various tubes to the outlet 22. A connecting element 15 is provided on the opposite side of the exchange bundle in order to connect the inlet 21, intended for the first fluid, to a connection surface, at the opposite end of said exchange bundle 13.

The operation of the heat exchanger according to the invention is based on the fact that the shapes of the plates 17 change between their first end 91 and their second end 92, as shown in FIG. 4. At the ends 91 and 92, the plates have a shape giving the possibility of making up, once they are combined, a tube with a relatively limited length “L” in order to allow the tubes to have a larger width. The surface of the section at the end of the tubes is indicated by the term of “secondary surface”. At the centre 93 of the plates 17, the plates 17 are adapted so as to form a tube with a relatively great length “L” and with a smaller width “l”. Within the present invention, the surface of the section of the centre of the tubes in a central area of the exchange bundle is indicated by the term of “main surface”. From the end 91 towards the central portion, the plate 17 comprises a transformation area. From the central portion 93 towards the end 92, each plate 17 comprises a second transformation area indicated by means of the reference number 95.

The technical effect of the specific shapes of the plates 17 is shown, in a schematic version, in FIGS. 5 and 6.

FIG. 5 shows as a sectional view, a portion of the exchange bundle 13. The inside of the tubes is indicated by means of the reference “A”. The various tubes are separated by means of channels referenced as “B”. The inside of the tubes “A” is suitable for guiding the first fluid and the channels “B” are suitable for guiding the second fluid as a counter-current. FIG. 5 shows that at the centre of the exchange bundle 13, the different fluids are well separated and that heat exchange is possible via the various walls.

The exchange bundle 13 is illustrated in FIG. 6, from the front and schematically. According to FIG. 6, by means of the different transformation areas 94 and 95, the volume of the assembly formed by the tubes and the channels is distributed specifically at the ends of the plates 17. This distribution of the volume differs from the distribution of the volume of the tubes and of the channels outside the ends of the exchange bundle.

The different surfaces “A” form, at their ends, the secondary surface which may, via a connecting element 14, 15, be connected to the inlet/outlet intended for the first fluid. The free space located around the surface “A” allows the entry of the different channels “B” and may be connected to the inlet/outlet intended for the second fluid.

By means of the secondary surface of the tubes, the second fluid may penetrate into the case within the space surrounding the connecting element 14 and the constriction of the tubes. The first fluid is then guided inside the channels “B” defined by the outside of the assembly of tubes “A” forming together the exchange bundle 13. The second fluid is guided between the different tubes towards a space surrounding the constriction and the connecting element 15 of the tubes towards the outlet 32.

FIG. 1 shows that the shape of the exchange bundle and the presence of a constriction of the tubes at their ends, by means of the transformation areas 94 and 95 of the plates 17, make available a free space inside the case, formed by means of the elements 11 and 12, and outside this constriction as well as the connecting element 14. This space generated inside the case allows connection of the inlet 31 intended for the second fluid. The second fluid, directed towards the inlet 31 towards the exchange bundle 13, may therefore circulate outside the connecting element 14 and outside the constriction of the tubes. In other words, this means that a heat exchange may occur between the first and the second fluid, through the walls of the connecting element 14 and this, directly after introducing the second fluid inside the heat exchanger 10. The same arrangement of the elements present at the opposite end of the exchange bundle 13 allows optimum heat exchange between both fluids and this as far as the outlet 32 intended for the second fluid.

The different elements as shown in FIG. 1 are assembled by means of a braising method as known in the prior art. With view to assembling the different elements inside the heat exchanger 10, said elements are pre-assembled in a position identical with their position inside the case 11, 12 and introduced into an oven. Aluminium and stainless steels are materials particularly suitable for forming the heat exchanger 10 according to the invention by means of the braising method.

FIG. 2 illustrates a perspective view of the heat exchanger 10 according to FIG. 1 in an assembled position. FIG. 2 shows that the heat exchanger 10 according to the invention is relatively compact. Further, the different inlets and outlets 21 (not shown), 22, 31 and 32 are grouped together in order to optimize the final installation of the heat exchanger 10 inside an automobile vehicle for example.

FIG. 3 shows in detail the exchange bundle 13, the plates 17 are stacked so as to form together in their inside, tubes allowing guidance of the first fluid, from a first end 131 to a second end 132 of the tubes and definition between the different tubes of the channels allowing guidance of the second fluid. Disturbers 18 may be present between the different plates 17. Said disturbers 18 have the purpose of improving the heat exchange between the first and the second fluid upon using the heat exchanger 10.

FIG. 7 shows a second embodiment of the heat exchanger according to the invention. FIG. 7 shows a heat exchanger 40, the structure of which is similar to that of the heat exchanger 10 according to FIG. 1. Only the plates forming the exchange bundle 43 are positioned differently as compared with those of the heat exchanger 10. Indeed, the plates are positioned vertically relatively to the length “L” of the heat exchanger 40.

The heat exchanger 40 comprises a first element 41 and a second element 42 forming as a combination a casing or case 41, 42 in order to form the outside of said heat exchanger 40. The case 41, 42 is suitable for containing an exchange bundle 43. This exchange bundle 43 includes a stack of plates 27 shown in FIGS. 8 and 9. The different plates 27 combined together, form tubes giving the possibility of guiding, in their inside, a first fluid from a first end to a second end of the exchange bundle 43. The different tubes define together channels allowing guidance of the second fluid outside the tubes, from the second end to the first end of the exchange bundle 43. The ends of the different tubes have a constriction in which said ends are grouped together in order to form a connection surface, said connection surface being suitable for being connected, by means of a connection, to a respective inlet/outlet intended for the first fluid. The ends having a constriction are clearly visible in FIGS. 8 and 9.

As illustrated in FIG. 7, an inlet 51 (partly visible) and an outlet 52, intended for the first fluid, are present in the second element 42. The inlet 51 is adapted so as to be connected to the connecting element 45 and for guiding the first fluid, from its inlet 51 towards the inside of the tubes of the exchange bundle 43, by means of this element 45. The outlet 52 is adapted so as to be connected to the connecting element 44 and for guiding, from the outlets of the different tubes and from the connecting element 44, the first fluid towards its outlet 52.

Moreover, the second element 42 comprises an inlet 61 and an outlet 62 (partly visible) allowing a second fluid to penetrate into the inside of the case. By means of the constriction present at the second end of the exchange bundle 43, the second fluid may be guided outside the connecting element 44 and outside the ends of the tubes in order to continue its path inside the channels defined by the different tubes. The second fluid may be guided towards the open space around the second end of the tubes and the outside of the connecting element 45 in order to leave the heat exchanger 40 through the outlet 62.

The heat exchanger 40 comprises sealing elements 46 giving the possibility of maintaining together the ends of the different tubes and of improving the seal of said tubes, thus avoiding possible leaks of fluids.

FIG. 8 shows the connection of the ends of the tubes 66 to a first connecting element 44 and to a second connecting element 45.

FIG. 8 illustrates a detailed view of the exchange bundle 43. The exchange bundle comprises tubes 66, each formed by the stacking of two plates comparable with the plates illustrated in FIG. 4. Disturbers 68 are visible between the different tubes 66, which disturbers facilitate the exchange between the first fluid inside the tubes 66 and the second fluid outside the tubes 66. The end of the different tubes 66 is shown in more detail in FIG. 7. FIG. 7 shows that the different ends of the tubes form together a secondary surface. This secondary surface is adapted for connection to the connecting element 44 as shown in FIG. 7. In order to improve the seal, the different ends of the tubes 66 are covered with a sealing element 46.

FIG. 9 shows the secondary surface obtained by the connection of the different ends of the tubes.

The different elements of the heat exchanger 40 as illustrated in FIGS. 7, 8 and 9 may be assembled by means of a braising method. In order to carry out this braising method, different elements are assembled in their different respective positions and introduced into an oven.

FIG. 10 shows a heat exchanger according to a third embodiment 70 of the invention, illustrated according to an exploded perspective view. As illustrated in FIG. 10, the heat exchanger 70 comprises a first element 71 and a second element 72 forming together a case. An exchange bundle 73 is present inside said case. The use of the heat exchanger 70 according to FIGS. 10 and 11 is similar to the use of the heat exchangers 10 and 40 as described above. A difference between the heat exchanger 70 and the heat exchangers 10 and 40 lies in the fact that the different tubes after their constriction and with their assembled surface are directly connected to an inlet/outlet present outside the case. This means that the connecting element allowing guidance of the second fluid according to FIGS. 10 and 11, is located outside the case. 

1. A heat exchanger allowing exchange of heat between a first and a second fluid, said exchanger comprising: a case and an exchange bundle positioned inside said case, wherein the exchange bundle comprises: a main surface comprising a main width and formed with a plurality of tubes suitable for guiding the first fluid inside these tubes, an inlet for the first fluid towards an outlet of the first fluid and allowing outside these tubes guidance of the second fluid, an inlet for the second fluid towards an outlet of the second fluid, wherein the tubes are, at at least one first end, assembled in order to form a secondary surface comprising a secondary width less than the main width for connection to the inlet and/or the outlet of the first fluid, wherein the secondary surface at the first end of the tubes is formed for generating a space between the case and the outer face of the secondary surface, which space is connected to the inlet and/or the outlet of the second fluid.
 2. The heat exchanger according to claim 1, wherein the tubes are, at a first end assembled in order to form the secondary surface for connection to the inlet of the first fluid wherein the secondary surface at the first end of the tubes is formed for generating a space between the case and the outer face of the secondary surface, which space is connected to the outlet of the second fluid; and wherein the tubes are, at the second end, assembled in order to form a secondary surface comprising a secondary width less than the width for connecting to the outlet of the first fluid, said secondary surface at the second end of the tubes generating a space between the case and the outer face of the secondary surface, which space is connected to the inlet of the second fluid.
 3. The heat exchanger according to claim 1, wherein said heat exchanger comprises a sealing element giving the possibility of covering the tubes at least at one end.
 4. The heat exchanger according to claim 1, wherein said heat exchanger comprises a connecting element giving the possibility of connecting at least one end of the tubes to an inlet or to an outlet by means of said connecting element.
 5. The heat exchanger according to claim 1, wherein the tubes are positioned relatively to each other so as to create channels between them, said channels include disturbers.
 6. The heat exchanger according to claim 1, wherein the exchange bundle is obtained by means of a plurality of plates positioned over each other and wherein the ends of said plates are provided with a rim giving the possibility of increasing the surface area between the plate and the inside of the case. 